Hello, I'm just posting here because I ran into the issue this morning and figured it might help someone.
I'm using AArch64 on my 3B+, and the raspberrypi-bootloader-20190904 update causes my Pi to boot without ethernet. I see something about `address not set` during the bootloader phase despite that I do have a static IP in my config.txt.
Anyways, to fix this I just rolled back the bootloader to last week's version like so:
$this->bbcode_second_pass_code('', 'sudo pacman -U /var/cache/pacman/pkg/raspberrypi-bootloader-20190828-1-any.pkg.tar.xz')
If anyone has any more insight into the issue that would be great